validation.py 文件源码

def validate_formset(self, cls, model):
        " Validate formset is a subclass of BaseModelFormSet. "
        if hasattr(cls, 'formset') and not issubclass(cls.formset, BaseModelFormSet):
            raise ImproperlyConfigured("'%s.formset' does not inherit from "
                    "BaseModelFormSet." % cls.__name__)